/*
 *  Copyright 2016 Google Inc. All Rights Reserved.
 *
 *  Licensed under the Apache License, Version 2.0 (the "License");
 *  you may not use this file except in compliance with the License.
 *  You may obtain a copy of the License at
 *
 *      http://www.apache.org/licenses/LICENSE-2.0
 *
 *  Unless required by applicable law or agreed to in writing, software
 *  distributed under the License is distributed on an "AS IS" BASIS,
 *  WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 *  See the License for the specific language governing permissions and
 *  limitations under the License.
 */

package com.google.android.apps.forscience.whistlepunk.sensorapi;

/**
 * Takes a stream of scalar values, and produces an altered stream of scalar values having the same
 * timestamps. Can be used to do simple frequency extraction, or re-scale units.
 */
public interface ValueFilter {
  ValueFilter IDENTITY =
      new ValueFilter() {
        @Override
        public double filterValue(long timestamp, double value) {
          return value;
        }
      };

  double filterValue(long timestamp, double value);
}
